Along with the advancement toward small-sized and highly accurate machinery devices and machinery parts, the lubrication used with sliding members is changing from fluid lubrication to boundary lubrication. Particularly, in the field of electronics and electronic parts such as a VTR or a magnetic disk, the use of a ferromagnetic metallic thin film with the intention of improving memory density requires highly accurate lubrication for sliding a magnetic recording medium on a magnetic head. For example, an evaporation tape and a hard disk are designed to achieve a higher output by minimizing the spacing between a magnetic recording medium and a magnetic head without losing durability and reliability. Therefore, a lubricant layer disposed on the surface of a magnetic layer is formed such that the thickness is only several nm (10 angstroms). Thus, an organic compound with high lubricity which is used to form this lubricant layer has become the major task of development.
As lubricants for metallic thin film type magnetic recording mediums, a long-chain carboxylic acid perfluoroalkyl amine salt shown in Formula 1 below, an aliphatic carboxylic acid with a fluoroalkylether group shown in Formula 2 below, and an aliphatic carboxylic acid with a fluoroalkyl group shown in Formula 3 below are disclosed due to their compatibility with metallic thin films (Laid-open Japanese Patent Application Nos. Hei 4-274018 and Hei 4-270243). ##STR2##
However, the lubricants shown in the above-noted Formulas 1, 2 or 3 were transferred onto a backing side when magnetic tapes were stored in an environment of high temperature and high humidity. The problem was that the lubricity deteriorated because the amount of lubricant present on the surface of the magnetic layer decreased through this transfer. This deterioration of lubricity becomes even more obvious as it results in lower steel endurance.